package main

import "fmt"

func VersionOrdinal(version string) string {
	// ISO/IEC 14651:2011
	const maxByte = 1<<8 - 1
	vo := make([]byte, 0, len(version)+8)
	j := -1
	for i := 0; i < len(version); i++ {
		b := version[i]
		if '0' > b || b > '9' {
			vo = append(vo, b)
			j = -1
			continue
		}
		if j == -1 {
			vo = append(vo, 0x00)
			j = len(vo) - 1
		}
		if vo[j] == 1 && vo[j+1] == '0' {
			vo[j+1] = b
			continue
		}
		if vo[j]+1 > maxByte {
			panic("VersionOrdinal: invalid version")
		}
		vo = append(vo, b)
		vo[j]++
	}
	return string(vo)
}

func main() {
	versions := []struct{ a, b string }{
		{"1.05.00.0156", "1.0.221.9289"},
		// Go versions
		{"1", "1.0.1"},
		{"1.0.1", "1.0.2"},
		{"1.0.2", "1.0.3"},
		{"1.0.3", "1.1"},
		{"1.1", "1.1.1"},
		{"1.1.1", "1.1.2"},
		{"1.1.2", "1.2"},
		{"1.10", "1.2"},
		{"1.00", "1.0"},
		{"1.0.0", "1.0"}, //如果多一个.那么久判断多的那个大

	}
	for _, version := range versions {
		a, b := VersionOrdinal(version.a), VersionOrdinal(version.b)
		//fmt.Println(a,"====", b ,"====", len(a), len(b))
		switch {
		case a > b:
			fmt.Println(version.a, ">", version.b)
		case a < b:
			fmt.Println(version.a, "<", version.b)
		case a == b:
			fmt.Println(version.a, "=", version.b)
		}
	}
}